Plumbing ID help - eviltoast

What’s the orange knob? Obviously the red and blue are hot and cold water for the washing machine. The orange knob is extremely hard to turn and I don’t want to force it without knowing what it is. Any ideas?

  • Another Person @lemmy.worldOP
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    1 year ago

    Pacific Northwest, so not too cold. I was hoping it was a whole house shut off but I don’t want to break it either.